Di((isocyanatobenzyl)-phenyl) carbodiimides and preparation of organic carbodiimides

ABSTRACT

ORGANIC ISOYANNATES (MONO- AND POLY-ISOCYANATES) ARE CONVERTED TO THE CORRESPONDING CARBODILIMIDES USING AS CATALYST A HETREROYCLIC PHOSPHORUS COMPOUND OF THE FORMULA:   Y&lt;(-CNH2N-N(-R&#34;)-P(=O)(-R&#39;&#39;)-)   WHEREIN CNH2N IS ALKYLENE HAVING 1 TO 12 CARBON ATOMS FROM 1 TO 3 OR WHICH FORM A CHAIN SEPARATING Y FROM N, R&#39;&#39; IS HYDROCARBYL (1 TO 18 CARBON ATOMS) WHICH CAN BE SUBSTITUTED BY HALO, NITRO ALKOXY, ALKYLMERCAPTO AND CYANO, R&#34; IS HYDROGEN, HYDROCARBYL (1 TO 18 CARBON ATOMS) OR -CONHR&#34;&#39;&#39; WHERE R&#34;&#39;&#39; IS HYDROCARBYL (1 TO 18 CARBON ATOMS) AND Y IS 0 OR -NR&#34; WHERE R&#34; IS AS ABOVE.

United States Patent 3,644,456 DI[(ISOCYANATOBENZYL)-PHENYL] CARBODI-IMIDES AND PREPARATION OF ORGANIC CARBODIIMIDES Henri Ulrich, Northford,Conn., assignor to The Upjohn Company, Kalamazoo, Mich.

No Drawing. Original application Aug. 12, 1964, Ser. No. 389,193, nowPatent No. 3,522,303, dated July 28, 1970. Divided and this applicationMar. 20, 1970, Ser. No. 21,477

Int. Cl. C07c 119/04; C07f 9/22 US. Cl. 260-453 AR 10 Claims ABSTRACT OFTHE DISCLOSURE Organic isocyanates (monoand poly-isocyanates) areconverted to the corresponding carbodiimides using as catalyst aheterocyclic phosphorus compound of the formula:

c n Y/ n\ \P/ 0 \R' wherein C H is alkylene having 1 to 12 carbon atomsfrom 1 to 3 of which form a chain separating Y from N, R is hydrocarbyl(1 to 18 carbon atoms) which can be substituted by halo, nitro, alkoxy,alkylmercapto and cyano, R" is hydrogen, hydrocarbyl (1 to 18 carbonatoms) or --CONHR"' where R' is hydrocarbyl (1 to 18 carbon atoms) and Yis O or NR" where R is as above.

CROSS-REFERENCES TO RELATED APPLICATIONS Patented Feb. 22, 1972 whereinC H represents an alkylene radical containing from 1 to 12 carbon atoms,inclusive, at least one and not more than 3 adjacent carbon atoms insaid alkylene radical forming a chain one end of which is attached to Yand the other end of which is attached to N thereby completing theheterocyclic ring; R is selected from the class consisting ofhydrocarbyl containing from 1 to 18 carbon atoms, inclusive, and halo-,nitro-, alkoxy-, alkylmercapto-, and cyano-substituted hydrocarbylcontaining from 1 to 18 carbon atoms, inclusive; R" is selected from theclass consisting of hydrogen, hydrocarbyl from 1 to 18 carbon atoms,inclusive, and the radical CONHR wherein R represents hydrocarbylcontaining from 1 to 18 carbon atoms, inclusive; and Y is selected fromthe class consisting of O and NR"- wherein R" has the significancedefined above.

The term alkylene radical containing from 1 to 12 carbon atoms,inclusive at least one and not more than 3 adjacent carbon atoms in saidalkylene radical forming a chain one end of which is attached to Y andthe other end of which is attached to N means methylene, ethylene, andtrimethylene, one or more of the hydrogen atoms of which divalentradicals can be replaced by alkyl groups such as methyl, ethyl, propyl,butyl, pentyl, hexyl, and isomeric forms thereof, provided that thetotal number of carbon atoms in the resulting alkylene radical does notexceed the stated limit. Examples of alkylene radicals falling withinthe definition are methylene, ethylidene, propylidene, isopropylidene,ethylene, 1,2-propylene, 1,2- butylene, l,3-butylene,2-ethyl-1,3-butylene, 2,4-hexylene, 1,3-octylene, 4,5-decylene,5,6-dodecylene, and the like.

The term hydrocarbyl containing from 1 to 18 carbon atoms, inclusive,means the monovalent radical obtained by removing one hydrogen atom fromthe parent hydrocarbon having the stated carbon atom content.Illustrative of such groups are alkyl groups Slllch as methyl, ethyl,propyl, butyl, pentyl, hexyl, octyl, decyl, dodecyl, hexadecyl,octadecyl, and the like, including isomeric forms thereof; alkenylgroups such as vinyl, allyl, butenyl, pentenyl, hexenyl, octenyl, andthe like, including isomeric forms thereof; aralkyl such as benzyl,phenethyl, phenylpropyl, benzhydryl, naphthylmethyl, and the like; arylsuch as phenyl, tolyl, xylyl, naphthyl, biphenylyl, and the like;cycloalkyl such as cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl,cyclooctyl and the like, including iso meric forms thereof; cycloalkenylsuch as cyclopentenyl, cyclohexenyl, cycloheptenyl, and the like,including isomeric forms thereof.

The term ha1o-, nitro-, alkoxy-, alkylmercapto-, and cyanosubstiutedhydrocarbyl containing from 1 to 18 carbon atoms means a hydrocarbylradical of the stated carbon atom content as above exemplified, whichhydrocarbyl radical is substituted by one or more halo, nitro,

3 alkoxy, alkylmercapto or cyano groups. Illustrative of suchsubstituted hydrocarbyl groups are chloromethyl, trichloromethyl,trifiuoromethyl, 2-chloroethyl, 2,3-dichlorobutyl, S-bromooctyl,6,7-dibromodecyl, methoxymethyl, Z-ethoxypropyl, 3-ethoxyhexyl,2-cyanoethyl, 3-cyanopropyl, Z-methylmercaptopropyl, 4-chlorophenyl,3-fluorophenyl, 4-cyanophenyl, 3-methoxyphenyl, 4-ethoxyphenyl,2-chloronaphthyl, Z-methylmercaptophenyl, 3,4-dimethoxyphenyl,3-chlorobenzyl, 4-fluorobenzyl, 2-methoxycyclopenty1, 3-bromocyclohexyl,4-chlorocyclohexenyl, Z-chloropropenyl, 4-brornobutenyl, 2-chlorovinyl,nitromethyl, 3-nitrobutyl, 4-nitrophenyl, 2-nitronaphthyl,3-methyl-4-nitrophenyl, 3-nitrocyclopenty1, 2-nitro-1-butenyl,4-methylmercaptobenzyl, Z-chlorobenzhydryl, 2,4-dibromobenzydryl and thelike.

The term alkoxy as used throughout the specification and claims meansalkoxy containing from 1 to 8 carbon atoms, inclusive, such as methoxy,ethoxy, propoxy, but oxy, pentyloxy, hexyloxy, heptyloxy, octyloxy, andisomeric forms thereof. The term alkylmercapto as used throughout thespecification and claims means alkylmercapto containing from 1 to 8carbon atoms such as methylmercapto, ethylmercapto, propylmercapto,butylmercapto, pentylmercapto, hexylmercapto, octylmercapto, andisomeric forms thereof.

The compounds of the invention having the Formula I are novel compoundshaving a variety of uses. Illustratively the novel compounds having theFormula I are useful as fire retardants; for example, they can be addedin a concentration of about 1% by weight or higher to foam mixes in theproduction of polyurethane foams as described by Dombrow, Polyurethanes,Reinhold Pub lishing Corporation, New York, pp. 1-105 (1957), to yieldpolyurethanes having fire retardant properties. In particular thecompounds of Formula I wherein R" is hydrogen and Y represents --NH, canby virtue of the two reactive hydrogen atoms therein, be incorporatedinto polyurethanes by adding them to the reaction mixture ofpolyisocyanate and polyol from which the polyurethane is preparedaccording to the procedures described above. The polyurethanes soobtained possess enhanced fire retardant properties. The compounds ofthe invention having the Formula I are also useful as catalysts in thepreparation of carbodiimides from isocyanates. This latter use of thecompounds of the invention will be discussed in more detail hereinafter.

The novel compounds having the Formula I above are also useful asstabilisers of polymeric materials, such as polyvinyl chloride andcopolymers thereof against the deleterious etfects produced thereto byexposure to ultraviolet radiation. For these purposes, the compounds ofFormula I are blended in the mixture containing the polyvinyl compound,plasticiser and other conventional adjuvants used in the preparation ofthe composition to be stabilised. Advantageously the compound of FormulaI is employed in the proportion of about 1 to about 10 parts by weightper parts of the polyvinyl compound.

The novel compounds of the invention can be produced by the reactionwhich is represented schematically by the following equation:

ZI-IHaI.

o R (II) (III) In the above equation C H R, and R" have the significanceabove defined and Hal represents halogen preferably chlorine.

In carrying out the preparation of the compounds (I) in accordance withthe reaction set forth in the above equation, the amine (II) and thehydrocarbyl phosphonic dihalide (III) are brought together in thepresence of a tertiary amine, as acid acceptor, and an inert solvent.11- lustrative of tertiary amines which can be used as acid acceptors inthe above process are pyridine, trialkylamines such as triethylamine,trimetylamine, triisopropylamine, tributylamine and the like,N-alkylpiperidines such as N- methylpiperidine, N ethylpiperidine, Nisopropylpiperidine, and the like, N-alkylmorpholines such asN-methylmorpholine, N-ethylmorpholine and the like, andN-dialkylanilines such as N,N-dimethylaniline, N,N-diethylaniline,N,N-dibutylaniline, and the like. Illustrative of inert organicsolvents, i.e. organic solvents which are inert under the conditions ofthe reaction, are hydrocarbons, particularly aromatic hydrocarbons, suchas benzene, toluene, xylene, naphthalene and the like, and halogenatedhydrocarbons such as methylene dichloride, ethylene dichloride, ethylenedibromide, carbon tetrachloride, chloroform, bromoform, chlorobenzene,bromobenzene, o-dichlorobenzene, and the like.

Generally speaking the reaction of the amine (II) and the phosphonicdihalide (III) is exothermic and does not require the application ofexternal heat to ensure completion. In certain cases, however, it isnecessary to heat the reaction mixture after the reactants have beenbrought together. Normally, it is advantageous to mix the reactants byadding the phosphonic dihalide (III) to a mixture of the amine (II) andthe tertiary amine acid acceptor. When this addition has been completedthe reac tion mixture can, if desired, be heated to temperatures up tothe order of 100 C., or to the reflux temperature of the reactionmixture if the latter is less than 100 C., in order to complete thereaction.

Advantageously, the amine (II) and the phosphonic dihalide (III) areemployed in approximately stoichiometric roportions in the abovereaction though higher or lower proportions can be employed withconsequent reduction in the yield of the desired compound (I). Theproportion of trialkylamine employed in the process of the invention isadvantageously of the order of 2 moles per mole of the phosphonicdihalide (III) though higher or lower proportions of tertiary amine canbe employed if desired.

The hydrohalic acid liberated in the process of the invention forms thecorresponding acid addition salt of the tertiary amine employed as acidacceptor and said salt normally separates as a precipitate from thereaction mixture. The precipitate is removed by filtration,centrifugation, and the like and the desired compound (I) is isolatedfrom the filtrate by procedures known in the art, for example, byevaporation of the filtrate and purification of the residue bydistillation, in the case of a liquid, or recrystallisation in the caseof a solid.

In an alternative procedure for carrying out the reaction between theamine (II) and the phosphonic dihalide (III) the latter is added to awell-stirred mixture of the former in the presence of a water-immiscibleinert organic solvent and an aqueous solution of an inorganic base suchas sodium carbonate, potassium carbonate, potassium hydroxide, sodiumhydroxide, lithium hydroxide and the like. Advantageously the inorganicbase is employed in the proportion of at least 2 equivalents per mole ofphosphonic dihalide. When the reaction is complete the organic layer isseparated and the desired compound (I) is isolated therefrom byprocedures known in the art, for example, those described above inconnection with the alternate procedures for the preparation of (I). Thewaterimmiscible inert organic solvents employed in the above procedureare advantageously hydrocarbons and halogenated hydrocarbons asexemplified hereinbefore.

The amines (II) which are employed as starting materials in thepreparation of the compounds (I) are, for the most part, known in theart or can be prepared by known methods. Thus the compounds (II) whereinY represents NR" and R" in both instances is hydrogen or alkyl, arealkylene diamines which can be prepared by conventional procedures knownin the art for the preparation of alkylene diamines; see, for example,Chemistry of Carbon Compounds, edited by E. H. Rodd, Elsevier PublishingCompany, New York, 1951, vol. I-A, pages 697-701. The amines (II)wherein Y represents O are alkanolamines which can be prepared byconventional procedures known in the art; see, for example, E. H. Rodd,ibid, vol. I-A, pages 689-691.

The amines (II) wherein R" represents --CONHR and R' is as hereinbeforedefined, including those wherein Y represents O or NR", can be preparedby reaction of the corresponding unsubstituted amine i.e. R"=H, with theappropriate isocyanate R'NCO under conditions well-known in the art forthe preparation of substituted ureas from amines and isocyanates see,for example, Bickel and French I. Am. Chem. Soc. 48,747,1926' Thehydrocarbyl phosphonic dihalides of the Formula III which are employedas starting materials in the preparation of the compounds (I) are also,for the most part, known in the art and can be prepared by conventionalprocedures, for example, that described in British Pat. 707,961 whichdescribes the preparation of hydrocarbyl phosphonic dihalides byreaction of the appropriate halohydrocarbon with phosphorus trihalide inthe presence of aluminum chloride, or that described in British Fat.648,- 328 which describes the air or oxygen blowing of a mixture of theappropriate hydrocarbon and phosphorus trihalide. Representative ofknown hydrocarbyl phosphonic dihalides having the Formula III are:methyl-, tertbutyl-, hexadecyl-, benzyl-, al1yl-, chloromethyl-,trichloromethyl-, 2-chloroethyl-, 2-bromoethyl-, butoxybutyl-,2-(butylthiovinyl)-, 1- chlorobutyl, (2-chloro-1-hexenyl),1-(chloromethyl)-butyl-, 4-chloro-3-nitrophenyl-, p-chlorophenyl-,2-chlorovinyl-, cyclohexyl-, 2-ethoxyethyl-, 2-methylpropenyl-, 2-naphthyl-, 2,2,2-trichloroethyl-, octadecyl-, phenyl-, 2- phenylbenzyl-,p-ethylphenyl-, l,l,2,2-tetrafluoroethyl-, 4- trifluoromethylpheny1-,4-trichloromethylphenyl-, dodecyl-, p-butoxyphenyl-,2-chlorocyc1ohexyl-, 2,4-dimethoxy-' phenyl-, 2,5-dibromophenyl-,m-tolyl-, 3,4-xylyl-, dichloro- 1,3-butadienyl-, p-bromobenzyl-,cyclopentyl-, and phenyloctadecyl-phosphonic dichlorides.

The system of nomenclature used throughout the specification and claimsis illustrated by the following examples:

2-ethyl-L3-dimethyl-13,2-

diazaphospholane 2-ox1de 2-ethyl-3-methyl-1,3,2-2-ethyl-3-rnethyl-1,3,2- oxazaphospholane 2-oxide oxazaphosphorinane2-0Xld6 4 /4\ CH N3 1N-CH OH -N3 1O \2/ r/ 4/ 0 CH 0 CH1,2,3-trimethyl-1,3,2- 2,3-dimethyl-1,3,2-oxazndlazaphosphetane 2'oxidephosphetane 2-oxide The following examples describe the manner andprocess of making and using the invention and set forth the best modecontemplated by the inventors of carrying out the invention but are notto be construed as limiting.

EXAMPLE 1 Z-ethyl-I ,3-dimethyl-1,3,2diazaphospholane Z-oxide To amixture of 6 grams (0.07 mole) of N,N'-dimethylethylenediamine and 14.14grams (0.14 mole) of triethylamine in 190 ml. of benzene was added 11grams (0.07 mole) of ethylphosphonic dichloride dropwise with stirringover a period of 6 minutes. The temperature rose from 28 to 38 C. Afterstirring for 20 minutes a precipitate of 18 grams (94%) of triethylaminehydrochloride was removed by filtration. Evaporation of the filtrate anddistillation of the residue under reduced pressure gave 7.8 g. (68.5% oftheory) of 2-ethyl-l,3-dimethyl-1,3,2-diazaphospholane 2-oxide in theform of a liquid having a boiling point of 93 C./ 0.5 mm.

Analysis.-Calcd. for C H N OP (percent): C, 44.42; H, 9.32; N, 17.20; P,19.10. Found (percent): C, 44.27; H, 8.74; N, 17.09; P, 19.24.

EXAMPLE 2 Z-chloromethyl-1,3-a'imethyl-I ,3,2-diazaph0spholane- 2-0xideTo a mixture of 8.8 grams (0.1 mole) of N,N'-dimethylethylenediamine and20.2 g. (0.2 mole) of triethylamine in 275 ml. of benzene was added 16.7g. (0.1 mole) of chloromethylphosphonic dichloride dropwise over aperiod of 12 minutes at 28 to 63 C. After stirring the resulting mixturefor 30 minutes a precipitate of 26.4 g. (94.5%) of triethylaminehydrochloride was removed by filtration. Evaporation of the filtrategave 18.4 g. of crude reaction product which was recrystallised fromligroin to obtain2-chloromethyl-1,3-dimethyl-1,3,2-diazaphospholane-2-oxide as whitecrystals, melting at to 77 C.

Analysis.-Calcd. for C H ClN OP (percent): N, 15.34; P, 16.97. Found(percent): N, 15.37; P, 16.54.

EXAMPLE 3 Z-trichloromethyl-I ,3-dimerhyl-1,3,2-diazaphospholane Z-oxideTo a mixture of 8.6 g. (0.1 mole) of N,N-dimethylethylenediamine and20.2 g. (0.2 mole) of triethylamine in 250 ml. of benzene was added asolution of 23.6 g. (0.1 mole) of trichloromethylphosphonic dichloridein 100 ml. of benzene over a period of 22 minutes at 27 to 54 C. Theresulting mixture was heated at reflux (80 to 82 C.) for 30 minutes andcooled to room temperature. The precipitate of 20.2 g. (73%) oftriethylamine hydrochloride was removed by filtration and the filtratewas evaporated to yield a crude crystalline residue. The latter wasrecrystallised from ligroin to yield 2-trichloromethyl-l,3-dimethyl-l,3,2-diazaphospholane 2-oxide as white crystals having amelting point of 88 C.

Analysis.Calcd. for' C H Cl N OP (percent): N, 11.13; P, 12.31. Found(percent): N, 11.19; P, 12.30.

EXAMPLE 4 2-ph enyl-l ,3-dimethyl-I,3,2-diazaphospholane 2-0xide Amixture of 17.6 g. (0.2 mole) of N,N-dimethylethylene diamine and 40.4g. (0.4 mole) of triethylamine in 410 ml. of benzene was added dropwise,with stirring, to 39 g. (0.2 mole) of phenylphosphonic dichloride over aperiod of 30 minutes at 27 to 59 C. After cooling the resulting mixtureto room temperature a. precipitate of 53.9 g. (96%) of triethylaminehydrochloride was removed by filtration. The filtrate was evaporated toyield 45.3 g. of crude reaction product. A 22 gram sample of the crudereaction product was distilled in vacuum to obtain 14.15 g. (70%) of2-phenyl-l,3-dimethyl-1,3,2-diazaphospholane 2-oxide in the form of asolid having a boiling point at 130 C./0.7 mm. and a melting point of 30to 38 C.

Analysis.Calcd. for C H N OP (percent): C, 57.13; H, 7.18; N, 13.32; P,14.73. Found (percent): C, 57.14; H, 7.03;N, 13.13; P, 14.74.

EXAMPLE 5 Z-phenyl-I,3-a'imethyl-1,3,2-diazaph0rinane Z-Oxide To amixture of 5.0 g. (0.054 mole) of N,N'-dimethylpropanediamine-1,3 and10.9 g. (0.108 mole) of triethylamine in 150 ml. of benzene was addeddropwise, with stirring, 10.5 g. (0.054 mole) of phenylphosphonicdichloride over a period of 8 minutes at 24 to 51 C. After cooling theresulting mixture to room temperature the precipitate of 12.7 g. (86%)of triethylamine hydrochloride was removed by filtration. Evaporation ofthe filtrate afforded 13.4 g. of a crude residue. Vacuum distillation ofthe residue gave 8.0 g. (71.5%) of2-phenyl-1,3-dimethyl-1,3,2-diazaphosphorinane-Z-oxide in the form of aliquid having a boiling point at 140 to 143 C./0.3 mm.

EXAMPLE 6 2-benzyl-1,3-dimethyl-1,3,2-diazaph0spholane 2-oxide Using theprocedure described in Example 1, but replacing ethylphosphonicdichloride by benzylphosphonic dichloride, there is obtained2-benzyl-l,3-dimethyl-1,3,2- diazaphospholane 2-oxide.

EXAMPLE 7 2-allyl-1,3-dimethyl-I,3,Z-diazaphospholane 2-0xide Using theprocedure described in Example 1, but replacing ethylphosphonicdichloride by allylphosphonic dichloride, there is obtained2-allyl-l,3-dimethy1-1,3,2-diazaphospholane 2-oxide.

EXAMPLE 8 Z-bromomethyl-1,3-dimethyl-1,3,2-diazaphosph0lane Z-oxia'eUsing the procedure described in Example 1, but replacingethylphosphonic dichloride by bromomethylphosphonic dichloride, there isobtained 2-bromomethyl-1,3- dimethyl-1,3,2-diazaphospholane 2-oxide.

EXAMPLE 9 Z-cyclohexyl-I,3-dimethyl-1,3,2-diazaphospholane 2-oxide Usingthe procedure described in Example 1, but replacing ethylphosphonicdichloride by cyclohexylphosphonic dichloride, there is obtained2-cyclohexyl-1,3-dimethyl-1,3,2-diazaphospholane 2-oxide.

EXAMPLE l0 Z-(Z-ethoxyethyl) -1,3-dimethyl-I,3,2-diazaphosph0laneZ-oxide Using the procedure described in Example 1, but replacingethylphosphonic dichloride by 2-ethoxyethylphos phonic dichloride, thereis obtained 2-(2-ethoxyethyl)-l, 3-dimethyl-1,3,2-diazaphospholane2-oxide.

EXAMPLE 11 Z-octadecyl-J,3-dimethyl-1,3,2-diaza phosph0lane Z-OxideUsing the procedure described in Example 1, but replacingethylphosphonic dichloride by octadecylphosphonic dichloride, there isobtained 2-octadecyl-1,3-dimethyl-1,3,2-diazaphospholane 2-oxide.

EXAMPLE l2 Z-naphthyl-J ,3 -.dimethyl-1 ,3,2-diazaph0sph0lane 2-0xideUsing the procedure described in Example 1, but replacing theethylphosphonic dichloride by Z-naphthylphosphonic dichloride, there isobtained 2-naphthyl-l,3-dimethyl-1,3,2-diazaphospholane 2-oxide.

Similarly, using the procedure of Example 1, but replacingethylphosphonic dichloride by the following phosphonic dihalides:

tert-butyl-, 2-chloroethyl-, 4-butoxybutyl-, 2-(butylthio)viny1-,2-chloro-1-hexenyl-, 4-chloro-3-nitrophenyl-, 4-chlorophenyl-,2-chlorovinyl-, 2,2,2-trichloroethyl-, o-phenylbenzyl-, 4-ethylphenyl-,

1, l,2,2-tetrafluoroethyl-, 4-trichloromethylphenyl-,4-trifiuoromethylphenyl-, dodecyl-, 4-butoxyphenyl-,2-chlorocyclohexyl-, 2,4-dimethoxyphenyl-, 2,5 -dibromophenyl-,m-tolyl-,

3 ,4-xylyl-, 4-bromobenzyl-, and cyclopentylphosphonic dichloride,

there are obtained:

EXAMPLE l3 Z-ethylJ-benzyl-],3,2-diazaph0sph0lane 2-0xz'de Using theprocedure described in Example 1, but replacingN,N'-dimethylethylenediamine by N-benzylethylenediamine, there isobtained Z-ethyl 1 benzyl-l,3,2- diazaphospholane 2-oxide.

EXAMPLE 14 Z-ethyl-I-benzyl-3-phenyl-1,3,2-diazaph0sph0lane 2-0xideUsing the procedure described in Example 1, but replacingN,N-dimethylethylenediamine by N-benZyl-N' phenylethylenediamine, thereis obtained 2-ethyl-1-benzyl-3-phenyl-l,3,2-diazaphospholane 2-oxide.

EXAMPLE 15 2-ethyl-I-cyclohexyl-1,3,2-diazaphospholane 2-0xz'de Usingthe procedure described in Example 1, but replacingN,N-dimethylethylenediamine by N-cyclohexylethylenediamine, there isobtained 2-ethyl-l-cyclohexyl- 1,3,2-diazaphospholane 2-0xide.

EXAMPLE 16 2-ethyl-1,3-diallyl-1,3,2-diazaphosph0lane 2-0xide Using theprocedure described in Example 1, but replacingN,N'-dimethylethylenediamine by N,N-diallylethylenediamine, there isobtained 2-ethyl-1,3-diallyl-l,3, 2-diazaphospholane 2-oxide.

Similarly, using the procedure described in Example 1, but replacingN,N-dimethylethylenediarnine by the following:

N-benzyl-N-diphenylmethyl-, N-benzyl-N'-u-ethylbenzyl-, N-4-biphenylyl-,

N,N'-bis( l,3-dimethylbutyl)-, N,N'-bis(Z-ethylcyclohexyl) N,N'-bis(2-ethylhexyl N-Z-cyclopentenl-yl-, N,N'-dibutyl-, N,N-dicyclohexyl-,N,N'-didodecyl-, N,N-diphenethy1-, N-1-naphthyl-, andN-o-tolylethylenediamine EXAMPLE 172,4-diethyl-1-butyl-I,3,2-diazaph0spholane 2-0xide Using the proceduresdescribed in Example 1, but replacing N,N dimethylethylenediamine byN-butyll,2- butanediamine, there is obtained 2,4-diethyl-l-butyl-l,3,2-diazapl1ospholane 2-oxide.

EXAMPLE 18 4-methyl-1,2,3-triethyl-1,3,2-diazaph0sph0rinane 2-0xideUsing the procedure described in Example 1, but replacingN,N'-dimethylethylenediamine by N,N-diethyl- 1,3-butanediamine there isobtained 4-methyl-1,2,3-triethyl-1,3,2-diazaphosphorinane 2-oxide.

EXAMPLE 19 2-ethyl-1-benzyl-1 -phenyl-1,3,2-diazaphosphetane-Z-oxideUsing the procedure described in Example 1, but replacingN,N-dimethylethylenediamine by N-benzyl-N'- 10 phenylmethylene diamine,there is obtained 2 ethyl 1- benzyl-3-phenyl-1,3,2-diazaphosphetane2-oxide.

Similarly, using the procedure described in Example 1, but replacingN,N-dimethylethylenediamine by the following:

N -cyclohexyl-2-methyl-1,2-propanediamine, -N ,N-diphenyl-1,2-propanediamine, N -octyl-l,2-propanediamine,Z-ethyl-1,3-hexanediamine, and N-benzyl-1,3-propanediamine,

there are obtained:

2-ethyl-1-cyclohexyl-4-dimethyl-1,3,2-diazaphospholane 2-oxide,2ethyl-1,3-diphenyl-4-rnethyl-1,3,2-diazaphospholane 2-oxide,2-ethyl-4-methyl-l-octyl-1,3,2-diazaphospholane, 2-oxide,2,5-diethyl-4-propyl-1,3,2-diazaphosphorinane 2-oxide, and2-ethyl-l-benzyl-l,3,2-diazaphosphorinane 2-oxide,

respectively.

EXAMPLE 20 2-ethyl-3-benzyl-1,3,2-0xazaph0sph0rinane 2-0xide Using theprocedure described in Example 1, but re placingN,N'-dimethylethylenediamine by 3-benzylaminol-propanol, there isobtained 2 ethyl 3 benzyl-l,3,2- oxazaphosphorinane 2-oxide.

EXAMPLE 21 2,3-diethyl-1,2,3-0xazaph0sph0lane 2-0xide Using theprocedure described in Example 1, but replacingN,N-dimethylethylenediamine by Z-ethylaminoethanol, there is obtained2,3-diethyl-1,3,2-oxazaphospholane 2-oxide.

Similarly using the procedure described in Example 1, but replacingN,N'-dimethylethylenediamine by the following known compounds:

2-aminoethanol, 2-pentylaminoethanol, Z-benzylaminoethanol,2-(4-biphenylylamino)ethanol, 2-sec-butylarninoethanol,2-(cyclohexen-1-ylamino)ethanol, 2-cyclohexylaminoethanol,2-dodecylaminoethanol, 2-hexylaminoethanol, 2-isobutylaminoethanol,

2-( l-naphthylmethylamino ethanol and 2-phenethylaminoethanol,

there are obtained:

. 2-ethyl-3-pentyl-,

2-ethyl-3-benZyl-,

2-ethyl-3- (4-biphenylyl 2-ethy1-3-sec-butyl-,

2-ethyl-3- (1 -cyclohexene l-yl) 2-ethyl-3-cyclohexyl-,

2-ethyl-3-dodecyl-,

2-ethyl-3-hexyl-,

2-ethyl-3-isobutyl-,

2-ethyl-3- l-naphthylmethyl and2-ethyl-3-phenethyl-1,3,2-oxazaphospholane 2-oxide,

respectively.

EXAMPLE 22 2-ethyl-3-m ethyl-5 -prpyl-1 ,3,2-0xazaph0sph0lane 2-0xideUsing the procedure described in Example 1, but replacing N,Ndimethylethylenediamine by 3 (aminomethyl)-3-pentanol, there is obtained2-ethyl-3-methyl-5- propyl-1,3,2-oxazaphospholane 2-oxide.

Similarly, using the procedure of Example 1, but replacingN,N-dirnethylethylenediamine by the following known compounds:

2-amino-1-octanol,

5 -amino-4-octanol, 4-methylamino-2-pentanol,2-isopropylamino-l-butanol, and 2-amino-3 -methyl-1-butanol,

there are obtained:

2-ethyl-4-hexyl-1,3,2-oxazaphospholane 2-oxide,

2-ethyl-4,5-dipropyl-1,3,2-oxazaphospholane 2-oxide,

2-ethyl-3,4,6-trimethyl-1,3,2-oxazaphosphorinane 2-oxide,

2,4-diethyl-3-isopropyl-1,3,2-oxazaphospholane 2-oxide,

and

2-ethyl-3,4diisopropyl-1,3,2-oxazaphospholane 2-oxide respectively.

EXAMPLE 23 Z-ethyl-3-phenylcarbamyl-1,3,2-oxazaphospholane Z-Oxide'Using the procedure described in Example 1, but replacingN,N'-dimethylethylenediamine by 1-(2-hydroxyethyl)-3-phenylurea, thereis obtained 2-ethyl-3-phenylcarbamyl-1,3,2-oxazaphospholane 2-oxide.

Similarly, using the procedure described in Example 1, but replacingN,N'-dimethylethylenediamine by the known compounds1-(3-hydroxybutyl)-3-phenylurea, 1- hydroxymethyl-3-phenylurea, or1-hydroxymethyl-3-tolylurea, there are obtained 2- ethyl3-phenylcarbamyl-6- methyl 1,3,2 oxazaphosphorinane 2-oxide, 2-ethyl-3-phenylcarbamyl-, and 2 ethyl 3-p-tolylcarbamyl-1,3,2- oxazaphosphetane2-oxide, respectively.

EXAMPLE 24 1,3-di(phenylcarbamyl) -2-ethyl-1,3,2-diazaphosph0lane2-0xz'ae Using the procedure described in Example 1, but replacingN,N-dimethylethylenediamine by l,1'-ethylenebis(3-phenylurea), there isobtained 1,3-di(phenylcarbamyl)-2-ethyl-l,3,2-diazaphospholane 2-oxide.

Similarly, using the procedure described in Example 1, but replacingN,N-dimethylethylenediamine by 1,1- ethylenebis(3 -ethylurea) and1,1'-ethylenebis(3 benzylurea) there are obtained:

1,3-di (ethylcarbamyl) -2-ethyl, and 1,3-di(benzylcarbamyl)-2-ethy1-1,3,2-diazaphospholane 2-oxide,

respectively.

EXAMPLE 25 Z-ethyl-I,3-dimethyl-1,3,2-diazaphosphorinane Z-oxide To amixture of 5.2 g. (0.056 mole) of N,N'-dimethylpropane-1,3-diamine and11.3 g. (0 112 mole) of triethylamine in 160 ml. of benzene Was addeddropwise, with stirring, a total of 8.2 g. (0.056 mole) ofethylphosphonic dichloride over a period of 7 minutes at 28 to 52 C. Theresulting mixture was cooled to room temperature and the triethylaminehydrochloride (13.6 g.) which had separated was removed by distillation.The filtrate was evaporated to dryness and the residue was distilled invacuo to obtain 5.9 g. (63.5%) of 2-ethyl-l,3-dimethyl-1,3,2-diazaphosphorinane 2-oxide having a boiling point of 98 C./0.3 mm.

Analysis.-Calcd. for C H N oP (percent): C, 47.71; H, 9.72; N, 15.98; P,17.57. Found (percent): C, 47.60; H, 9.64; N, 15.83; P, 17.39.

The compounds of the invention having the Formula I as described abovepossess useful properties as catalysts in the synthesis of carbodiimidesfrom the corresponding organic isocyanates. It has been suggestedpreviously in the art than organophosphorus compounds can be used ascatalysts in the conversion of organic isocyanates to the correspondingcarbodiimides. It has not been suggested previously, however, thatcyclic phosphorus compounds of the Formula I containing oxygen and/ ornitrogen atoms in the ring can be used for this purpose. Further, it hasbeen found that the use of the Compounds I as catalysts in the formationof carbodiimides shows unexpected and unobvious advantages which will bediscussed in more detail below.

Accordingly, in a further aspect of the present invention, there isprovided an improved process for the conversion of organic isocyanatesto carbodiirnides wherein the improvement consists in employing acompound of the Formula I as catalyst.

The conversion of an organic isocyanate to the correspondingcar-bodiimide involves reaction between two iso cyanate groups withliberation of CO and is illustrated by the following equation:

wherein R represents an organic radical, preferably an aromatic,aliphatic or araliphatic hydrocarbon residue, the only limitation onsubstitution in said radical being that it be free of substituents whichare reactive with the isocyanate group. Thus, the organic radical shouldbe free of substituents containing active hydrogen i.e. which displayactivity according to the Zerewitinotf test (Berichte 40, 2023, 1907).Representative of organic isocyanates which can be employed are methyl,ethyl, isopropyl, butyl, hexyl, octyl, octadecyl, allyl, Z-pentenyl,cyclopentyl, cyclohexyl, l-cyclopentenyl, 2-cyclopheptenyl, benzyl,phenethyl, 3-phenylpropyl, benzhydryl, 2-naphthylmethyl, naphthyl,phenyl, p-tolyl, o-tolyl, 3-nitrophenyl, 4-methoxyphenyl,4-allyloxyphenyl, 3,4-xylyl, 2-chlorophenyl decahydronaphthyl,trifiuoromethyl, 2-chloroethyl, 3-nitropropyl isocyanates and the like.It is to be understood that a mixture of isocyanates can be employed, ifdesired, to form unsymmetrically substituted carbodiimides.

In addition to the monoisocyanates exemplified above, polyisocyanatescan be employed to produce linear or crosslinked polycarbodiimides. Aparticularly useful embodiment of the process of the invention is theconversion of polyisocyanates, especially diisocyanates to oligomericpolycarbodiimides terminated at each end by an isocyanate group.

Representative of the polyisocyanates which can be used in the improvedprocess of the invention are: tolylene-2,4- diisocyanate,methylenediphenylene 4,4 diisocyanate,methylenediphenylene-2,2-diisocyanate, methylenediphenyl2,2-diisocyanate, methylenediphenylene-2,4-diisocyanate,hexamethylenediisocyanate, biphenylene-4,4-diisocyanate,3,3-dimethoxybiphenylene-4,4-diisocyanate, and the like diisocyanatessuch as those listed in the tables of Siefken, Ann. 562, 122435, 1949.

In carrying out the improved process of the invention the desiredorganic isocyanate is treated with a catalytic amount of the compound ofFormula I above. The amount of catalyst of Formula I employed isadvantageously of the order of about 0.1 to about 1.0 part by weight perparts by weight of isocyanate though higher proportions of catalyst canbe employed, if desired. The admixture of catalyst and isocyanate isaccomplished by conventional procedures. For example, if the twocompounds are solid the mixing can be accomplished by micronisa tion,ballmilling and the like. Where one or both compounds are liquid or canbe melted, simple solution of one component in the other can beaccomplished readily.

Generally speaking it is necessary to heat the mixture of catalyst (I)and organic isocyanate to elevated temperatures, advantageously to atemperature within the range of about 100 C. to about 250 C. to etfectformation of the desired carbodiimide. In certain cases, however,reaction will take place at lower temperatures and in some instanceswill take place without the application of external heat. The completionof reaction is generally marked by the cessation of evolution of carbondioxide and, when followed spectrographically, by the disappearance ofthe band characteristic of the isocyanate group from the infra redspectrum. The desired carbodiimide can be purified by procedureswell-known in the art such as recrystallisation in the case of solidsand distillation in the case of liquids.

The use of the compounds of the formula I as catalysts in the formationof carbodiimides from isocyanates is characterised by the very highyields and rates of conversion of isocyanate to carbodiimide. In manyinstances the yields are quantitative or substantially so and, in themajority of cases, are greater than 80%. In addition, certain of thecompounds of Formula I possess other advantages which makes their use ascatalysts particularly attractive. For example, the compounds of FormulaI wherein R and R" are lower alkyl, i.e. alkyl from 1 to 8 carbon atoms,inclusive, and Y represents or N-lower-alkyl, are compounds having alower boiling point than the carbodiimides in the formation of whichthey are employed as catalysts.

Thus, such compounds of Formula I, which can be represented by thefollowing formula:

(Lower-alkyl) -N N- (Lower alkyl) l/ O wLower-alkyl) and (Lower-alkyD-N0 0 (Lower-alkyl) wherein C H is as hereinbefore defined, and preferablywherein C H represents ethylene or propylene, can be readily recoveredfrom the reaction mixture by distillation, leaving the carbodiimideresidue to be purified by conventional procedures such asrecrystallisation. The catalyst so recovered can then be re-used in theconversion of further isocyanate to carbodiimide. The advantages of suchcatalysts are readily apparent and need no further explanation.

Another group of catalysts falling within the general Formula I whichpossess special advantages are those wherein R represents aryl from 6 to12 carbon atoms, inclusive, as hereinbefore defined and exemplified andR" represents alkyl from 1 to 18 carbon atoms or aryl from 6 to 12carbon atoms inclusive i.e. the compounds having the formula:

wherein C 'H is as hereinbefore defined, aryl represents aryl from 6 to12 carbon atoms, inclusive, and A is selected from the class consistingof alkyl from 1 to 18 carbon atoms, inclusive and aryl from 6 to 12carbon atoms, inclusive. The above compounds generally possess higherboiling points than the carbodiimides in whose production they are used.This enables the carbodiimide to be separated from the reaction mixtureby distillation leaving a residue which contains the original catalystand which can be re-used in the catalytic formation of carbodiimide fromisocyanate. The application of such catalysts to the operation ofsemi-continuous processes is one of the obvious advantages which theypossess.

In a modification of the improved process of converting the organicisocyanates to the corresponding carbo diimides especially adapted forthe operation of continuous or semi-continuous processes, the productcarbodiimide can be employed as the reaction medium. Thus, for example,a mixture of by weight of starting isocyanate can be dissolved in theproduct carbodiimide in the presence of the catalyst. This enables ahigher reaction temperature to be attained and thereby to increase thereaction date.

The carbodiimides produced according to the improved process of theinvention can be used as is known in the art, to prevent ageing andhydrolysis of elastomers in accordance with procedures described, forexample, by Newman et al. preprint of Fourth Rubber TechnologyConference, London, May 22-25, 1962.

The carbodiimides produced according to the process of the invention areparticularly useful in the stabilisation of polyurethanes. Generally,the carbodiimide is incorporated in the mix from which the polyurethaneis prepared and becomes dispersed throughout the resulting polyurethane.A particularly interesting and novel class of carbodiimides which isdescribed for the first time in this application is that of oligomericlow molecular weight isocyanate terminated carbodiimides which areproduced by heating, at from about 100 C. to about 250 C., adiisocyanate having the formula:

wherein R represents lower-alkyl and R is selected from the classconsisting of lower-alkyl and hydrogen, and wherein the two R groups arenot necessarily identical and the two R groups are not necessarilyidentical, with a catalytic amount (i.e. from about 0.1 to about 1.0part by Weight per 100 parts by weight of diisocyanate) of a compound ofFormula I until such time as infrared spectral analysis (or othersuitable analytical means) shows that approximately 50% of the originalisocyanato groups in the starting material have been consumed. At thisstage the reaction is terminated by cooling the reaction mixture,advantageously by addition of an inert organic solvent as hereinbeforedefined and exemplified and/or by the application of external cooling.The solvent (if present) and catalyst are removed from the reactionmixture by distillation leaving a residue which comprises a mixture ofdifunctional (in regard to isocyanate) oligomeric low molecular weightisocyanate terminated carbodiimides of which the chief component has thefollowing structure:

wherein R and R are as hereinbefore defined. The compounds of the aboveFormula V can be isolated from the mixture obtained as described aboveby conventional procedures, for example, by recrystallisation,chromatography, countercurrent distribution and the like.

The isocyanate terminated carbodiimides prepared as described above,either in the form of a crude mixture obtained by conversion of thestarting diisocyanate (IV) or in the form of the purified dimer of theFormula V above, can be incorporated chemically into polyurethanes byvirtue of the two isocyanate groups present therein. Thus, theisocyanate terminated carbodiimides can be used as part of thepolyisocyanate component normally employed in the preparation ofpolyurethanes from polyisocyanates and polyols according to proceduresknown in the art; see Dornbrow, supra. The polyurethanes therebyobtained have carbodiimide stabilising agents incorporated chemicallyinto the polyurethane molecules and are thus distinguished from priorcomponents wherein the carbodiimide stabilising agent is incorporatedmerely physically.

The diisocyanates (IV) which are employed as starting materials in thepreparation of the isocyanate terminated carbodiimides as describedabove, are for the most part, known in the art. The tetraalkyl compounds(IV; R =RFalkyl) are prepared as described in British Pat. 852,651. Thetrialkyl and dialkyl compounds of Formula IV are prepared in similarmanner by condensation of formaldehyde with the appropriate2-alkylaniline or mixture of 2-alkylaniline and 2,6-dialkylaniline togive the corresponding 4,4'-diamino 3,3'-dialkyldiphenylmethanes and 4,4-diarnino-3,3',5-trialkyldiphenylmethanes which are then phosgenatedusing procedures known in the art, see, for example Siefken supra, toyield the corresponding diisocyanates.

The following examples illustrate the use of the compounds of Formula Ias catalysts in the conversion of organic isocyanates to thecorresponding carbodiimides. It is to be understood that these examplesare given for purposes of illustration and are not limiting and that anyof the compounds (I) can be used as catalyst in the conversion tocarbodiimides of any of the organic isocyanates defined and exemplifiedabove using the procedures illustrated in the following examples.

EXAMPLE 26 To 133 g. (1 mole) of o-tolyl isocyanate was added 0.67 g.(0.5% by weight) of 2-phenyl-l,3-dimethyl-1,3,2-diazaphospholidine2-oxide and the mixture was heated to reflux (184 0.); within 140minutes the reaction temperature rose to 250 C. and an infraredspectrum, by the appearance of a strong band at 47 4 (N=C=N) anddisappearance of the isocyanate band at 4.4 4, indicated almost completeconversion. Vacuum distillation of the reaction mixture gave 100.3 g.(90%) of di-o-tolylcarbodiimide, boiling at 132 to 140 C./0.5 to 0.6 mm.

EXAMPLE 27 Illustration of reuse of the catalyst of Example 26 to thedistillation residue from the reaction described in Example 26 was added133 g. (1 mole) of o-tolyl isocyanate and the reaction mixture washeated to reflux temperature (184 C.); within 120 minutes thetemperature rose to 250 C. Vacuum distillation of the reaction mixturegave 107.8 g. (97%) of di-o-tolylcarbodiimide, boiling at 134 to 146C./0.3 mm.

EXAMPLE 28 To 26.6 g. (0.2 mole) of o-tolylisocyanate was added 0.125 g.(-0.5% by weight) of 2-ethyl-1,3-dimethyl- 1,3,2-diazaphospholane2-oxide. The reaction mixture was heated to reflux (184 C.) and withinminutes a temperature of 250 C. was obtained. Vacuum distillation of thereaction product gave a first fraction of 2.0 g. boiling at 38 to 122C./ 0.2 mm. of a mixture of o-tolyl isocyanate, catalyst and someproduct, and a second fraction of 18.6 g. (84%) of puredi-o-tolylcarbodiimide, boiling at 122 to 135 C./0.2 to 0.4 mm.

EXAMPLE 29 Illustration of reuse of catalyst To 26.6 g. (0.2 mole) ofo-tolyl isocyanate was added the first fraction obtained in thedistillation of the reaction product in Example 27. The resultingmixture was heated to reflux (180 C.) and within 26 minutes atemperature of 260 C. was obtained. Vacuum distillation of the productgave 21.6 g. (97%) of di-o-tolylcarbodiimide boiling at 128 to 138C./0.2 to 0.3 mm.

EXAMPLE 30 To 26 g. (0.2 mole) of o-tolyl isocyanate was added 0.100 g.(-0.5% by weight) of 2-chloromethyl-1,3-dimethyl-1,3,2-diazaphospholane2-oxide. The reaction mixture was heated to reflux (180 C.) and within180 minutes a temperature of 250 C. was obtained. Vacuum distillation ofthe product gave 17.2 g. (77.5 of di-otolylcarbodiimide boiling at 128to 130 C./0.3 mm.

EXAMPLE 31 To 25 g. (0.21 mole) of phenyl isocyanate was added 0.125 g.of 2-ethyl-1,3-dimethyl-1,3,2-diazaphospholane 2-oxide and the mixturewas heated for 10 minutes at to 230 C. Vacuum distillation of thereaction product gave 1 6.6 g. (81.7%) of diphenylcarbodiimide. boilingat 118 C./0.7 mm.

EXAMPLE 32 To 25 g. (0.2 mole) of cyclohexyl isocyanate was added 0.125g. of 2-ethyl-1,3-dimethyl-1,3,2-diazaphospholane 2-oxide and themixture was heated for 13 hours at 169 to 251 C. Distillation of theproduct gave 15.9 g. (77.5%) of dicyclohexyl carbodiimide, boiling at 96to 98 C./0.3 mm.

EXAMPLE 33 Use of a carbodiimide as the reaction medium To a mixture of12.5 g. (0.1 mole) of cyclohexyl isocyanate and 12.5 g. dicyclohexylcarbodiimide was added 0.200 g. of2-ethyl-1,3-dimethyl-1,3,2-diazaphospholane 2-oxide and after heatingfor five hours at to 270 C. the product was distilled in vacuum to give19.6 g. (69% conversion) of dicyclohexyl carbodiimide, boiling at 98 to100 C./0.3 mm.

EXAMPLE 34 To 25 g. (0.85 mole) of octadecyl isocyanate was added 0.125g. of 2-ethyl-1,3-dimethyl-1,3,2-diazaphospholane 2-oxide and, afterheating for 2 hours at 200 to 250 C., the isocyanate was found byinfrared analysis to be completely converted to the carbodiimide. Theresidue was recrystallised from ligroin to give dioctadecylcarbodiimide, melting at 50 to 53 C.

EXAMPLE 35 Di-(m-chlorophenyl) carbodiimide A mixture of 30.7 g. (0.2mole) of m-chlorophenylisocyanate and 0.037 g. of2-ethy1-1,3-dimethyl-1,3,2-diazaphospholane 2-oxide was heated for 35minutes at 180 to 200 C. after which time the infra red specrtum showedthe absence of the characteristic isocyanate band. The reaction productwas distilled under reduced pressure. The first fraction (0.25 g.)contained unchanged catalyst. The second fraction (24.55 g.) having aboiling point of 174 to 176 C./ 1.4 mm. was di-(m-chlorophenyl)carbodiimide which solidified to crystals having a melting point of 43to 46 C.

EXAMPLE 36 Di-[2,6-diethyl-4-(3,5-diethyl-4-isocyanat0benzyl) phenyl]carbodiimide A mixture of 72.4 g. (0.2 mole) of3,3',5,5'-tetraethyldiphenyl-methane-4,4'-diisocyanate (British Pat.852,651) and 0.724 g. of 2-ethyl1,3-dimethyl-1,3,2-diazaphospholane2-oxide was heated under nitrogen for 60 minutes at 230 C. at the end ofwhich time the infrared spectral analysis of an aliquot showed thedisappearance of 44% of the original isocyanate. The reaction mixturewas quickly cooled to room temperature. There was thus obtained amixture of difunctional (in terms of isocyanato groups) oligomeric lowmolecular weight isocyanate terminated carbodiimides containingprincipally di-[2,6-diethyl-4-(3,5-diethyl-4-isocyanatobenzyl) phenyl]carbodiimide. A sample of 10 g. of the above mixture was dissolved in100 ml. of dry acetone and the resulting solution 17 was allowed tostand at C. for a short period. The solid which had separated wasisolated by filtration. There was thus obtained 2.54 g. ofdi-[2,6-diethyl-4-(3,5-diethyl-4- isocyanatobenzyl) phenyl] carbodiimidein the form of a crystalline solid having a melting point of 88 to 90 C.

Analysis.-Calcd. for C H N O N, 8.32%. Found: N, 8.67%.

The acetone mother liquors from the above crystallisation were treatedwith 100 ml. of a 1:1 mixture of meth' anol and carbon tetrachloride andthe mixture was refluxed for 4 hours. The resulting solution wasconcentrated by evaporation and the solid which separated was isolatedby filtration to yield 6.84 g. of a mixture of methylurethanes having amelting point of 107 to 118 C. and an infrared spectrum showing a sharpband at 4.65 corresponding to the N=C=N group.

Using the procedure described in Example 36, but replacing3,3',5,5-tetraethyldiphenylmethane-4,4'-diisocyanate by3,3,5,5'-tetramethyl-3,3',5,5'-tetrapropyland3,3,5,5'-tetrabutyldiphenylmethane-4,4-diisocyanate (all prepared asdescribed in BJP. 852,651) there are obtained the corresponding mixturesof difunctional oligomeric low molecular weight isocyanate terminatedcarbodiimides from each of which mixtures the principal component isisolated by crystallisation from acetone to yield di-[2,6- dimethyl 4(3,5 dimethyl-4-isocyanatobenzyl)phenyl] carbodiimide, di[2,6-dipropyl-4-(3,5-dipropyl-4-isocyanatobenzyl) phenyl] carbodiimideand di-[2,6-dibutyl-4- (3,5 4 'dibutyl-4-isocyanato-benzyl)phenyl]carbodiimide, respectively.

EXAMPLE 37 Di- [2-ethyl-4-(3-ethyl-4-isocyanatobenzyl) phenyl]carbodiimide A mixture of 61.2 g. (0.2 mole) of3,3'-diethyldiphenylmethane-4,4'-diisocyanate and 0.306 g. of2-ethyl-l,3-dimethyl-1,3,2-diazaphospholane 2-oxide was heated undernitrogen at 150 C. for 1.5 hours. At the end of this time infraredspectral analysis of a sample showed a decrease of 51% of the isocyanateabsorption at 4.42 and the appearance of the characteristic N=$Nabsorption band at 4.65 4. To the mixture so obtained was added 100 ml.of o-dichlorobenzene which was subsequently removed by distillationunder reduced pressure with simultaneous removal of the phospholaneoxide catalyst. There was thus obtained a mixture of difunctionaloligomeric low moleclular weight isocyanate terminated carbodiimidescontaining principally di-[2-ethyl-4-(3-ethyl-4-isocyanatobenzyl)phenyl] carbodiimide. The latter was purified by recrystallisation fromacetone.

Similarly, using the procedure described in Example 37 above butreplacing 3,3-diethyldiphenylmethane-4,4- diisocyanate by 3,3'-dimethyland 3,3 diisopropyldiphenylmethane-4,4'-diisocyanate, there are obtaineddi- [2 methyl-4-(3-methyl-4-isocyanatobenzyl)phenyl] carbodiimide and2-[2-isopropyl-4-(3-isopropyl-4-isocyanatobenzyl)phenyl] carbodiimide,respectively.

I claim:

1. A compound having the formula:

from the class consisting of alkyl isocyanates from 1 to 18 carbonatoms, inclusive, alkenyl isocyanates from 3 to 5 carbon atoms,inclusive, cycloalkyl isocyanates from 5 to 6 carbon atoms, inclusive,cycloalkenyl isocyanates from 5 to 7 carbon atoms, inclusive, aralkylisocyanates from 7 to 13 carbon atoms, inclusive, aryl isocyanates from6 to 10 carbon atoms, inclusive, arylene diisocyaanates from 6 to 12carbon atoms, inclusive, methylenebis(phenyl isocyanates) which containfrom 0 to 2 loweralkyl groups in the phenyl nuclei, and hexamethylenediisocyanate, the improvement which comprises employing as catalyst insaid conversion from about 0.1 to about 1.0 part by weight per parts byweight of said organic isocyanate of a compound having the formula:

wherein C H represents alkylene containing from 1 to 12 carbon atoms,inclusive, at least one and not more than 3 adjacent carbon atoms insaid alkylene radical forming a chain one end of which is attached to Yand the other end of which is attached to N thereby completing theheterocyclic ring; R is selected from the class consisting ofhydrocarbyl containing from 1 to 18 carbon atoms, inclusive, and halo-,nitro-, alkoXy-, alkylmercapto-, and cyano-, substituted hydrocarbylcontaining from 1 to 18 carbon atoms, inclusive; R" is selected from theclass consisting of hydrogen, hydrocarbyl from 1 to 18 carbon atoms,inclusive, and the radical CONHR wherein R represents hydrocarbylcontaining from 1 to 18 carbon atoms, inclusive; and Y is selected fromthe class consisting of O- and --NR" wherein R" has the significanceabove defined.

5. In a process for the catalytic conversion of an organic isocyanatehaving no active hydrogen containing substituents reactive with anisocyanate, to the corre sponding carbodiimide, said organic isocyanatebeing selected from the class consisting of alkyl isocyanates from 1 to18 carbon atoms, inclusive, alkenyl isocyanates from 3 to 5 carbonatoms, inclusive, cycloalkyl isocyanates from 5 to 6 carbon atoms,inclusive, cycloalkanyl isocyanates from 5 to 7 carbon atoms, inclusive,aralkyl isocyanates from 7 to 13 carbon atoms, inclusive, arylisocyanates from 6 to 10 carbon atoms, inclusive, arylene diisocyanatesfrom 6 to 12 carbon atoms, inclusive, methylenebis(phenyl isocyanates)which contain from 0 to 2 loweralkyl groups in the phenyl nuclei, andhexamethylene diisocyanate, the improvement which comprises employing ascatalyst in said conversion from 0.1 to about 1.0 part by weight per 100parts by weight of said organic isocyanate of a compound having theformula:

n zn (lower-alkyl) N 0 (lower-alkyl) (lower-alkyl) wherein C Hrepresents alkylene containing from 1 to 12 carbon atoms, inclusive, atleast one and not more than 3 adjacent carbon atoms in said alkyleneradical forming a chain separating the N atoms in the heterocyclic ringand lower-alkyl represents alkyl from 1 to 18 carbon atoms, inclusive.

6. The process of claim 5 wherein the catalyst is 2-ethyl-1,3-dimethyl-1,3,2-diazaphospholane 2-oxide.

7. In a process for the catalytic conversion of an organic isocyanatehaving no active hydrogen containing substituents reactive with anisocyanate, to the corresponding carbodiimide, said organic isocyanatebeing selected from the class consisting of alkyl isocyanates from 1 to18 carbon atoms, inclusive, alkenyl isocyanates from 3 to 5 carbonatoms, inclusive, cycloalkyl isocyanates from 5 to 6 carbon atoms,inclusive, cycloalkenyl isocyanates from 5 to 7 carbon atoms, inclusive,aralkyl isocyanates from 7 to 13 carbon atoms, inclusive, arylisocyanates from 6 to 10 carbon atoms, inclusive, arylene diisocyanatesfrom 6' to 12 carbon atoms, inclusive, methylenebis(phenyl isocyanates)which contain from to 2 loweralkyl groups in the phenyl nuclei, andhexamethylene diisocyanate, the improvement which comprises employing ascatalyst in said conversion from about 0.1 to about 1.0 part by weightper 100 parts by weight of said organic isocyanate of a compound havingthe formula:

wherein C H represents alkylene containing from 1 to 12 carbon atoms,inclusive, at least one and not lnore than 3 adjacent carbon atoms insaid alkylene radical forming a chain separating the N atoms in theheterocyclic ring; A is selected from the group consisting of alkylcontaining from 1 to 8 carbon atoms, inclusive, and aryl from 6 to 12carbon atoms, inclusive, and B is aryl containing from 6 to 12 carbonatoms, inclusive.

8. The process of claim 7 wherein the catalyst is 2-phenyl-1,3-dimethyl-1,3,2-diazaphospholane 2-oxide.

9. In a process for the catalytic conversion of an organic isocyanatehaving no active hydrogen containing substituents reactive With anisocyanate, to the corresponding carbodiimide, said organic isocyanatebeing selected from the class consisting of alkyl isocyanates from 1 to18 carbon atoms, inclusive, alkenyl isocyanates from 3 to 5 carbonatoms, inclusive, cycloalkyl isocyanates from 5 to 6 carbon atoms,inclusive, cycloalkenyl isocyanates from 5 to 7 carbon atoms, inclusive,aralkyl isocyanates from 7 to 13 carbon atoms, inclusive, arylisocyanates from 6 to 10 carbon atoms, inclusive, arylene diisocyanatefrom 6 to 12 carbon atoms, inclusive, methylenebis (phenyl isocyanates)which contain from 0 to 2 lower-alkyl groups in the phenyl nuclei, andhexamethylene diisocyanate, the improvement which comprises the step ofreacting said organic isocyanate with from 0.1 to 1.0 part by weight perparts by weight of isocyanate of a catalyst having the formula:

References Cited UNITED STATES PATENTS 2,840,589 6/1958 Smelt 2604533,056,835 10/1962 Monagle et a1 260551 3,502,722 3/1970 Newmann 260453XR FOREIGN PATENTS 1,145,353 9/1963 Germany.

CHARLES B. IPARKER, Primary Examiner D. H. TOR-RENCE, Assistant ExaminerUS. Cl. X.R.

252-426; 260-25 AT, 2.5 A], 2.5 BB, 45.7 P, 77.5 AT, 453 P, 543 P, 551P, 566 R

